title: An aromatic amino acid in the coiled-coil 1 domain plays a crucial role in the auto-inhibitory mechanism of STIM1.
abstract: STIM1 (stromal interaction molecule 1) is one of the key elements that mediate store-operated Ca²⁺ entry via CRAC (Ca²⁺- release-activated Ca²⁺) channels in immune and non-excitable cells. Under physiological conditions, the intramolecular auto-inhibitions in STIM1 C- and STIM1 N-termini play essential roles in keeping STIM1 in an inactive state. However, the auto-inhibitory mechanism of the STIM1 C-terminus is still unclear. In the present study, we first predicted a short inhibitory domain (residues 310-317) in human STIM1 that might determine the different localizations of human STIM1 from Caenorhabditis elegans STIM1 in resting cells. Next, we confirmed the prediction and further identified an aromatic amino acid residue, Tyr³¹⁶, that played a crucial role in maintaining STIM1 in a closed conformation in quiescent cells. Full-length STIM1-Y316A formed constitutive clusters near the plasma membrane and activated the CRAC channel in the resting state when co-expressed with Orai1. The introduction of a Y316A mutation caused the higher-order oligomerization of the in vitro purified STIM1 fragment containing both the auto-inhibitory domain and CAD(CRAC-activating domain).We propose that the Tyr³¹⁶ residue may be involved in the auto-inhibitory mechanism of the STIM1 C-terminus in the quiescent state. This inhibition could be achieved either by interacting with the CAD using hydrogen and/or hydrophobic bonds, or by an intermolecular interaction using repulsive forces, which maintained a dimeric STIM1.
authors.affiliation: College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Junwei
authors.initials: J
authors.lastname: Yu
authors.forename: Haining
authors.initials: H
authors.lastname: Zhang
authors.forename: Mingshu
authors.initials: M
authors.lastname: Zhang
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Deng
authors.forename: Huiyu
authors.initials: H
authors.lastname: Wang
authors.forename: Jingze
authors.initials: J
authors.lastname: Lu
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Pingyong
authors.initials: P
authors.lastname: Xu
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D000071740:ORAI1 Protein; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D059010:Single-Cell Analysis; D000071737:Stromal Interaction Molecule 1; D014443:Tyrosine / Q000737:chemistry* / Q000235:genetics
chemical_list: D029742:Caenorhabditis elegans Proteins; D015220:Calcium Channels; D008565:Membrane Proteins; C519796:ORAI-1 protein, C elegans; D000071740:ORAI1 Protein; D000071737:Stromal Interaction Molecule 1; C516629:stim-1 protein, C elegans; D014443:Tyrosine